The exhaust system of automobile engine is provided with an exhaust gas purifying device for purifying exhaust gas components. As the exhaust gas purifying device, a catalytic converter, a diesel particulate filter (hereinafter referred to as DP filter) system and the like are available.
The catalytic converter purifies exhaust gas components (carbon hydride, carbon monoxide, nitric oxide and the like) emitted from a gasoline engine or a diesel engine. The catalytic converter comprises a ceramic-made catalyst carrier carrying catalyst for purifying exhaust gas components and a metallic shell for accommodating it. A holding and sealing mat material for holding the catalyst carrier is disposed between the catalyst carrier and the metallic shell. The catalyst carrier is mounted in the metallic shell in a condition that the holding and sealing mat material is wound around it. Because the thermal expansion coefficient is different between the metallic shell and the ceramic-made catalyst carrier, a difference in thermal expansion between the two occurs under high temperatures. Thus, development of the holding and sealing mat material having cushioning performance capable of absorbing the difference in thermal expansion has been demanded.
The DP filter system purifies exhaust gas by catching diesel particulates emitted from a diesel engine. The DP filter system comprises a ceramic-made DP filter for catching diesel particulates and a metallic shell for accommodating the ceramic-made DP filter. A holding and sealing mat material for holding the DP filter is disposed between the DP filter and the metallic shell. The DP filter is mounted in the metallic shell in a condition that the holding and sealing mat material is wound around it. Because the thermal expansion coefficient is different between the metallic shell and the ceramic-made DP filter, a difference in thermal expansion between the two occurs under high temperatures. Thus, as is the case with the catalytic converter, development of the holding and sealing mat material having a cushioning performance capable of absorbing the difference in thermal expansion has been demanded.
Both the holding and sealing mat material of the catalyst carrier and the holding and sealing mat material of the DP filter have cushioning performances and large volumes. Thus, it is difficult to mount the catalyst carrier or the DP filter in the metallic shell, which the holding and sealing mat material is wound around.
In views of such conventional problems, an object of the invention is to provide a catalytic converter containing the holding and sealing mat material which facilitates work for mounting the catalyst carrier into the metallic shell and has an excellent cushioning performance and further, a diesel particulate filter system containing the holding and sealing mat material which facilitates work for mounting the DP filter into the metallic shell and has an excellent cushioning performance.